Mobile radiation surveillance network

ABSTRACT

A detection system and method having at least one detection unit, and a control centre unit. The detection unit includes at least one sensor configured to generate sensor data correlated to sensed conditions, a locator for actively determining location data corresponding to the location of the detection unit, and a communicator configured to communicate the sensor data and location data. The control centre includes a receiver for receiving the sensor data and the location data, together with a control processor which is configured to determine a threat level correlated to the sensor data.

RELATED APPLICATIONS

This application is a continuation of application Ser. No. 10/867,643,filed on Jun. 16, 2004. This application also claims priority from U.S.provisional patent application No. 60/520,243 filed on Nov. 17, 2003which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to the field of surveillancesystems, with common but by no means exclusive application to systemsfor detecting nuclear, radiation, chemical or biological conditions inthe environment.

BACKGROUND OF THE INVENTION

Since the terrorist events of Sep. 11, 2001, the likelihood of futureterrorist attacks is acknowledged to be higher than in the past. As aresult, the public has greater expectations for security, prevention,interdiction and incident site management. Radiological and other agentshave a particularly high potential for psycho-social impacts onpolitical and economic systems. The malicious dispersal or theclandestine placement of radiological materials or other agents could beused to attack private, public and economic targets.

Radiological, nuclear, biological or chemical agents could be acquiredby terrorists through clandestine theft or low level military operationsand moved, possibly undetected, to urban population areas or to targetsof high symbolic value.

The applicants have accordingly recognized a need for improved systemsand methods of detecting and tracking nuclear, radiological, biologicalor chemical threats.

SUMMARY OF THE INVENTION

In one aspect, the invention is directed towards a detection systemhaving at least one detection unit and a control centre.

The detection unit includes at least one sensor configured to generatesensor data correlated to sensed conditions; a locator for activelydetermining location data corresponding to the location of the detectionunit; and a communicator configured to communicate the sensor data andlocation data.

The control centre includes a receiver for receiving the sensor data andthe location data, and a control processor configured to determine athreat level correlated to the sensor data.

In another aspect, the invention is directed towards a detection unithaving at least one sensor, a locator, and a communicator. The sensor isconfigured to generate sensor data correlated to sensed conditions. Thelocator is configured to actively determine location data correspondingto the location of the detection unit. The communicator is configured tocommunicate the sensor data and location data.

In yet another aspect, the invention is directed towards a detectionunit comprising at least one sensor, a locator, a control processor anda display unit. The sensor is configured to generate sensor datacorrelated to sensed conditions. The locator is configured to activelydetermine location data corresponding to the location of the detectionunit. The control processor is operatively coupled to the sensor and tothe locator. The display is operatively coupled to the control processorand configured to display graphical data correlated to both the sensordata and the corresponding location data.

In yet a further aspect, the invention is directed towards a method ofdetecting threatening conditions, comprising the steps of:

-   -   a. providing a control centre;    -   b. providing at least one mobile detection unit, wherein the        detection unit comprises at least one sensor configured to        generate sensor data correlated to sensed conditions;    -   c. actively determining location data corresponding to the        location of the detection unit;    -   d. communicating the sensor data and the location data to the        control centre;    -   e. determining a threat level correlated to the sensor data.

Preferably, the method also includes the step of generating a graphicaldisplay correlated to both the sensor data and the location data.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example only,with reference to the following drawings, in which like referencenumerals refer to like parts and in which:

FIG. 1 is a schematic diagram of a detection system made in accordancewith the resent invention.

FIG. 2A is a schematic diagram of a mobile detection unit used inconnection with the detection system of FIG. 1.

FIG. 2B is a schematic diagram of a vital point detection unit used inconnection with the detection system of FIG. 1.

FIG. 3 is a schematic diagram of sample historical sensor reading datastored in the main data storage unit of FIG. 1.

FIG. 4 is a schematic diagram of a stand-alone detection unit made inaccordance with the present invention.

FIG. 5 is a representative screen display of a display unit of FIG. 1.

FIG. 6 is a logical flow diagram of a method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, illustrated therein is a detection system, referredto generally as 10, made in accordance with the present invention. Thedetection system 10, typically comprises a plurality of detection units12, and a control centre 14 and a main data storage unit 16. Thedetection units 12 and control centre 14 are typically operativelycoupled via a communications network 17 such as the internet, a localradio or wired communications network, or cellular communicationsnetwork, or a combination thereof, which provides a communications linkbetween the units 12 and the centre 14.

The detection units 12 may be of a mobile detection unit type 18 or astationary vital point detection unit type 20.

Referring now to FIG. 2A, illustrated therein is a mobile detection unit18. The mobile detection unit 18 includes a suitably programmeddetection unit central processing unit (CPU) 30 comprising random accessmemory (RAM) and read only memory (ROM) storing device manager software31. The CPU 30 is operatively coupled to one or more sensors 32, alocator 34, a timer 36, a communicator 38, a detection unit data storage40, and a power source 41.

Each sensor 32 measures the current level of a potentially harmful agent(eg. radiological, nuclear, chemical or biological) in the immediateenvironment, and generates corresponding sensor data 42, preferably atspecified intervals on a continuous basis while the detection unit 18 isin operation. Such sensors 32 are commercially available, for example,the Eberline 40G series of radiation detectors and the associated familyof external radiation detectors are available as off-the-shelfcomponents.

The locator 34 is preferably an active positioning determining devicesuch as a global positioning system (GPS), for example, a Trimble LassenSQ GPS. However other systems for actively and accurately determiningthe location of the detection unit 18 may be used, for example such asthe LORAN navigation system or other triangulation systems, whichgenerate location data 44 corresponding to the location of the detectionunit 18.

The timer 36 may be programmed as part of the processor 30 utilizing theprocessor's 30 clock functionality, and is configured to generate timingdata 46 which corresponds to the time at which each sensor data point 42is generated. Alternatively, if the locator 34 is a GPS system, thelocator 34 could also generate the timing data 46, as will beunderstood.

The processor 30 receives the sensor data 42, the location data 44 andthe timer data 46, and organizes the data 42, 44, 46 and including anyerror messages into a data message 51. The processor 30 then causes thecommunicator 38 to communicate the data message 51 (containing the data42, 44, 46 and any error messages) to the control centre 14 forprocessing. The communicator 38 will be a wireless data transmitter forexample such as a wireless modem or wireless Ethernet device.Preferably, the processor 30 is configured to encrypt the data message51, and correspondingly, to decrypt any data messages received from thecontrol centre 14.

Typically, the communicator 38 will transmit the data message 51 viaradio or cellular transmission. Typically, such a transmission will bereceived and converted into an internet message for delivery to thecontrol center 14. In the event the communicator 38 is unable toestablish or maintain a communications link with the control centre 14,the processor 30 is preferably programmed to store the data 42, 44, 46and/or the data message 51 in the detection unit data storage 40 forretrieval and communication by the communicator 38 once communicationswith the control centre 14 have been reestablished.

The detection unit data storage 40 will preferably also store basicalarm threshold data 48, which preferably stores an alarm threshold datapoint 48 corresponding to a dangerous sensor data level 42. If thesensor 32 generates a sensor reading 42 which exceeds (or is less thanas the case may be) the alarm threshold data point 48, the processor 30will preferably be programmed to trigger a local alarm 50 or otherwisewill preferably be programmed to notify the user of the potentialdanger.

Additionally, the communicator 38 may receive location-based alarmthreshold data points 48 from the control centre 14 which it will storein the detection unit data storage 40 (or alternatively in the detectionunit's processor 30 RAM storage). The basic and location-based alarmthreshold data 48 is stored locally on the detection unit 18 to enablethe processor 30 to detect a harmful environment and trigger a localalarm 50 for safety reasons, even when communication with the controlcentre 14 is interrupted or degraded and the control centre 14 would beunable to trigger such an alarm.

A power source 41 sufficient to power the operation of the detectionunit 18 is also provided. The power source 41 preferably includes arechargeable battery system. In some instances, the detection unit 18(and correspondingly, the power source 41, which will typically comprisea significant portion of the detection unit's 18 weight) may beconfigured in size and weight to be easily carried by a person, forexample, in a backpack. In such instance, it is expected that such aperson could either walk or travel on bike or horseback. In addition, orin the alternative to a rechargeable battery system, in detection units18 intended for use with a motor vehicle the power source 41 may includecabling and/or adaptors for connecting the detection unit 18 to thevehicle's electrical system for the supply of electrical power.

In general, each detection unit 12 measures current levels ofundesirable agents (ie. chemical, biological, radiological or nuclear),and sends these measurements, coupled with current time and location, tothe Control Center 14. The Control Center 14 receives and organizes thedata from a network of Detection Units 12.

Referring now to FIG. 2B, illustrated therein is a vital point detectionunit 20. Vital Point Detection Units 20 (VPDU 20) are staticallydeployed, and are intended to protect fixed assets. VDPUs 20 aregenerally similar to the mobile detection units 18. However, because aVPDU's 20 location is static, no GPS-style locator 34 is required.Accordingly, the locator 34′ may simply comprise location data 44corresponding to the location of the VDPU 20 which has beenpredetermined and stored in the detection unit data storage 40. For thesake of clarity, such a locator 34′ is not considered to be active forthe purpose of this application.

Additionally, wireless communication is typically not needed in VDPUs20. Accordingly, the communicator 38′ may take the form of a wiredcommunication device, such as a wired Ethernet device. As well, in thecase of a VDPU 20, the power supply 41 may include a electrical plug forplugging into a standard wall socket.

Referring again to FIG. 1, the control centre 14 includes three mainsoftware components, each of which may be programmed and run on a maincontrol centre CPU 70, or alternatively may be programmed and run onseparate, but operatively coupled CPUs: a relay module 72, a datamanager 74, a threat manager 76.

Typically, the main data storage unit 16 comprises long term memory andforms part of the control centre 14, although it should be understoodthat the database 16 may reside locally or be remotely coupled to thecontrol centre 14. The control centre 14 also includes a communicationsunit 78, typically having both wired and wireless communicationsdevices, such as wireless modems, wired or wireless Ethernet devices,radio or satellite or infrared transmitters and receivers.

The relay module 72 is programmed to manage the communication of databetween the communications unit 78 and the communicator 38 of each ofthe detection units 12. The data manager 74 manages the main datastorage unit 16. The data manager 74 provides service to the relaymodule 72 and the control centre managers 80 (discussed in greaterdetail below), and allows them to add, retrieve, modify and deletevarious monitoring information.

The threat manager 76 determines if the sensor data 42 indicates a levelof agent that is higher than normal, or in the case of radiation,indicates the presence of a signal that is stronger than backgroundradiation. The threat manager 76 determines a threat level for allsensor data 42 measurements, which is stored with each sensor datameasurement 42 in the main data storage unit 16 by the data manager 74.In its simplest embodiment, the threat manager 76 may determine threatlevel by comparing the sensor measurements 42 to previously determinedthreshold level data points stored in the main data storage 16.

In a more complicated embodiment, the threat manager 76 determinesthreat level by analyzing sensor measurements 42, in conjunction withthe corresponding location and time when the sensor measurements 42 weretaken. The threat manager 76 may also use data from other sensors thatmeasure current weather conditions, and it may allow manual overridesfor known and accepted radiation anomalies (such as known transportationof non-illicit material). This calculated threat level is then coupledwith the measurement 42, location and time and stored in the main datastorage 16 by the data manager 74.

The threat level analysis typically proceeds in four steps. These foursignal processing steps are preferably employed continuously throughoutthe operation of the system 10. This continuous operation allows forimprovement in sensitivity and specificity of detection of threat eventsduring the entire operational lifetime of the system 10 throughincreased statistical precision in characterizing the expected radiationenvironment. The four steps are set out below.

First, the sensor measurements 42 are associated with a statisticaluncertainty. Further, the effects of radiation sensor movement, sensorefficiency of detection, instrumental measurement averaging time,directional sensitivity, and other instrumental factors as may benecessary are accounted for in order to obtain an estimate of theradiation level at a specific location and its uncertainty.

Second, the estimates of the radiation levels and their uncertaintiesare associated with season of year, time of day, prevailing climaticconditions, and measurements obtained from other sensors such as staticradiation sensors. Using these factors the seasonal and temporalvariations in the radiation environment may be characterized.

Third, the short term temporal and spatial variations in radiationmeasurement levels arising from the legitimate movement and placement ofradiation sources in the environment are identified by association ofradiation measurement data with those radiation sources

Fourth, anomalous radiation sources both static and moving arecharacterized by significant deviations from the expected radiationenvironment as identified by the above three steps. Anomalous radiationsources may differ in such factors as, but not limited to, magnitude ofradiation sensor measurement data, velocity, pattern of movement withinthe environment, temporal variation in radiation measured level andradiation spectrum.

The system 10 provides for the use of conventional signal processingtools to conduct the above four steps. These tools include but are notlimited to statistical estimates of errors and uncertainties,statistical tests of significance of association, difference, etc.,seasonal factor extraction, temporal and spatial averaging anddeconvolution techniques. These tools are typically applied globally tothe data set of sensor measurements distributed spatially over the areamonitored and temporally over the time span of monitoring

The present system provides for the capability to employ adaptivealarming levels. First, the important spatial, meteorological andtemporal variations within a high value target area and which variationsmay be as great as ten to one, may be used to provide for deviations ofthe radiation or other types of sensor measurements relative to theexpected levels specific in time and location as determined by routineoperation of the present system.

In addition, the system provides for the adjustment of the aboverelative alarming levels on the basis of a risk/cost/benefitdetermination. Intelligence estimates of the probability of theperpetration of a radiological, chemical, biological or nuclear attackand other intelligence information from outside the system may be usedto dynamically adjust the relative measurement alarming levels. Thisadaptive alarming operation provides for the more sensitive detection ofanomalous events with acceptance of the costs of higher false positiverates in periods of greater perceived risk to the high value targetarea.

In routine surveillance operation, and in the absence of threateningincidents, the system 10 provides a cost effective means for theassembly of a data set characterizing the normal or expected environmentof the area under surveillance with unprecedented spatial resolution,temporal resolution and statistical significance. Moreover the data arereported automatically by autonomous operation of the system leading tothe important advantages of reliability, reproducibility, consistencyand negligible field operative skill and time requirements.

The detailed understanding and the catalog of the signatures of benignradiation, nuclear, biological and/or chemical measurements resultingfrom operation of the system 10 provide a basis upon which theidentification of the signatures of anomalous and illicit events can bemade. This leads to a lower rate of occurrence of undesirable and costlyfalse alarms or false positive indications of illicit events. As well,these features lead to a lower rate of occurance of dangerous and costlyfailures to alarm in the presence of illicit events or false negativeindications of illicit events.

Pixon signal processing tools may instead be used to conduct the abovefour steps. Pixon signal analysis is discussed for example in Puetter,R. C., and Yahil, A., “The Pixon Method of Image Reconstruction”, Proc.ADASS '98, in Astronomical Data Analysis Software and Systems VIII, D.M. Mehringer, R. L. Plante, and D. A. Roberts, Ed.s, ASP ConferenceSeries, Vol. 172, pp. 307-316, which is incorporated herein byreference.

These Pixon tools obtain the best estimate of a radiation measurementfor example at each specific spatial and temporal point in the set ofradiation measurements by modeling the data available in the localneighborhood of that spatial and temporal point. The model developed ofthe local data is that model which is the simplest possible which isconsistent with the statistical uncertainties inherent in the data. Thethreat manager 76 is also preferably programmed to provide the abilityto query the data manager 42 for the stored threat level of eachdetection unit's 12 latest sensor readings.

The data manager 74 is preferably the only control centre 14 systemcomponent that has direct access to the main data storage 16. Alloperations involving reading, writing, and manipulating data within themain data storage 16 will preferably be performed exclusively by thedata manager 74. The data manager 74 provides services to the relaymodule 72 and to each control centre manager 80 that allow them to add,modify, view, and delete data stored in the main data storage 16.

The data manager 74 controls the storing of sensor data 42, deviceconfiguration data, errors, and commands for the detection unit CPUs 30.The data manager 74 will receive the data messages 51 from the relaymodule 72 and then parse the sensor readings 42, corresponding locationand time data, and error messages from the data messages 51 and storethem in the main data storage 16.

Referring now to FIG. 3, illustrated therein is a representative sampleof the type of historical data which may be stored in the main datastorage 16. The database 16 contains the detection unit identifier 92,the sensor data 42, units of measurement 43, the location data 44(latitude 94 and longitude 96) (corresponding to the sensor data 42),and the timer data 46 also corresponding to every reading 42.

The relay module 72 may also be programmed to periodically query thedata manager 74 for a list of commands to be sent to the detection unitCPUs 30. The data manager 74 will also store all application preferencesand settings data required by the control centre managers 80. Thecontrol centre managers 80 may query the data manager 74 for sensorreadings 42, and detection unit 12 configuration. In addition eachcontrol centre manager 80 will be able to send commands to the detectionunits 12 and update configuration information.

The relay module 72 captures the data messages 51 in raw data streamsfrom the detection unit CPUs 30 and sends them to the data manager 74.In addition, the relay module 72 has the ability to forward commandsfrom the data manager 74 to the detection unit CPUs 30.

The relay module 72 monitors for incoming socket requests and thenforwards them to the data manager 74. The relay module 72 will alsoperiodically poll the data manager 74 for commands that need to be sentto individual detection unit CPUs 30.

The relay module 72 is preferably programmed to accept incoming socketrequests from detection units 12.

It will spawn an instance of a “Request Manager” to read the datamessages 51 from the detection unit 12. The relay module 72 will ensurethat the Request Manager terminates properly.

Once a connection request is detected, the relay module 72 willpreferably create a specialized thread, called “Request Manager”, fordealing with the device requesting the connection.

The Request Manager thread is capable in running in two modes. In N-bitmode the Request Manager will wait for a data message 51 from adetection unit 12. Once the message 51 has been received, the RequestManager thread will upload available commands to the detection unit 12,then it will close the connection. In Permanent Listen mode the RequestManager thread will always have the connection open to receive newreadings from the client detection unit. In this mode the RequestManager thread will periodically check if there are commands availableto send to the client device. In Permanent Listen mode, the RequestManager thread will only close the connection when an error isencountered.

The control center 14, also receives requests from each control centermanager 80 (a user interface application) to retrieve information. Thecontrol center manager 80 will query the data manager 74 for storedradiation readings and detection unit 12 configuration. In addition, thecontrol center manager 80 is able to send commands to the detectionunits 12 and update configuration information.

Typically, each control centre manager 80 is coupled to an input/outputdevice 82, such as a computer having a keyboard 84 and mouse and adisplay monitor 86 for displaying data to the end users. As discussedbelow, the input/output device 82 may be a portable device such as a PDAor cellular phone having a display screen. Via the display screen 86,the control centre manager 80 is programmed to display a radiationmonitoring screen to the end user. FIG. 5 illustrates a representativeexample of a radiation monitoring screen 90.

The screen 90 shall display a table 91 of the current radiation readingsbeing displayed on a map 100 which is synchronized with the locationdata 44 for each of the detection units 12. The table 91 contains thedetection unit identifier 92, the location data 44 (latitude 94 andlongitude 96), sensor data 42, units of measurement and the timer data46 for every reading

The screen 90 also displays a labeled marker or other indicator on thecurrent map 100, showing the location of each of the detection units 12,and indicating each unit's 12 current alarm level. The screen shalldisplay a trail on the current map 100, showing the recent path of eachof the detection units 12, and indicating each unit's 12 alarm level ateach point on that path. In the example illustrated on FIG. 5, therelative strength of the alarm levels is illustrated by the size of thegeometric shapes marking each trail, but colour or other appropriateindicator may be used. In the example illustrated on FIG. 5, threedifferent geometric shapes (circles, squares, triangles) depict thepaths of the three different detection units 12. The larger circles andlarger squares are intended to illustrate sensor readings 42 which weredetermined to represent a higher threat level than the sensor readings42 represented by small squares and small circles.

Every reading that can be located on the selected map 100 is illustrateduntil it expires (e.g. after 2 minutes or some other selected timelimit). If alarms are set, they are illustrated on the map 100accordingly. The trails indicate past readings.

As noted, the control centre manager 80 is also programmed to providethe user the ability to query the data manager 74 to view historicalreadings. The display will provide the ability to query for readings,and the ability to query the results.

The control centre manager 80 is programmed with a replay manager whichdisplays a replay of a previous set of data, between two dates/times setby the user, on the display monitor 86. The replay screen should besubstantially similar to the monitoring screen 90 illustrated in FIG. 5.The replay should preferably be paused, rewound, and fast forwarded. Thereplay speed may also preferably be increased several times for speedyviewing.

Illustrated on the replay screen are a slider control, and play, pause,and stop buttons which allow the user to have a media player-likecontrol over the replay. A progress bar within the slider controlindicates the progress of the data streaming, as in media player. Thereplay manager allows the user to select a speed of playback, which canbe changed at any time.

The control centre manager 80 is also programmed to allow the user toselect a map 100 (or arial photograph or view of a larger map, etc.) onwhich to view the sensor data 42. This can be changed at any time.

Preferably, the control centre 14 is also programmed with a threatlocating module 102. This module 102 is expected to be used when aradiological or nuclear terrorist event has occurred or has beensuspected to have occurred.

This threat locating module 102 has access to all historical and currentradiation readings and associated times and locations. It will use thesedata, their associated statistical analyses, and physical modeling ofterrorist event scenarios in order to determine estimates of thelocation, quantity, and isotope of the radiological or nuclear material.It will do this analysis for several scenarios, where each scenario isbased on a different assumption of the nature of the source: singlestationary location, two stationary locations, single RadiologicalDispersal Device (RDD), two RDDs, etc.; single source being transported,two sources being transported, etc.; widely dispersed source (i.e. as apowder, aerosol, etc.).

Additionally, the system 10 provides the benefit and advantage of makingavailable substantially in real time and potentially on a national orinternational scale the data, information and estimates related toidentified or suspected terrorist attacks. This benefit will be ofparticular advantage during multiple attack events and in solicitingexpert opinion from multiple remote jurisdictions.

This analysis would preferably be illustrated graphically, in a mannersimilar to that of the radiation monitoring screen 90. The user mayselect the scenario description, and see the probable locationsdisplayed on a map 100. In this manner, the user may see a logicalpattern for one or more scenarios, and direct policing authorities andfirst responders accordingly.

Equipping policing authorities and first responders with displays mayprove to be advantageous. The control centre manager interface 80 caneasily be run on computers that are common in police cars. However, aportable display would be valuable for pedestrian and equine deployment.

This portable display 82, running on a Personal Digital Assistant (PDA)or on a Wireless Application Protocol (WAP) enabled cell phone, may runthe standard control centre manager interface 80, or be programmed torun a special light version of the software.

This light version of control centre manager interface 80 wouldselectively display information related to the user's own detection unit12: actual sensor readings 42, current threat level (alarm level),location information 44 (all displayed textually and/or graphically).

Illustrated in FIG. 4 is a schematic diagram of an alternativestand-alone version of the detection unit 12′ of the present invention.For cost or other reasons, it may not be feasible for certainapplications to have a centralized control centre 14. Accordingly, asingle stand-alone detection unit 12′ of the present invention may bedesired.

As will be understood, the stand-alone detection unit comprises manysimilar components as that of the mobile detection unit 18, but with theprocessing capability of the control centre CPU 70, and the greaterstorage capacity of the main data storage 16. Accordingly, thestand-alone CPU 30′ is programmed with the threat manager 76 and thedata manager 74 modules. The detection unit 12′ is also provided with adisplay monitor 86 and an input device 84, for example such as akeyboard or touch-sensitive screen, which are operatively coupled to theCPU 30′.

The detection unit 12′ will preferably generate a screen displaysubstantially similar to the radiation monitoring screen 90, but as willbe understood, will only display the data such as the sensor readings 42and location data 44 and time data 46 generated by the detection unit12′.

Referring now to FIG. 6 (in conjunction with FIGS. 1 and 2A & 2B),illustrated therein is one embodiment of the general process, referredto generally as 200, which the detection system 10 performs. A controlcentre 14 is provided (Block 202), together with at least one detectionunit 12 having a sensor 32 for generating sensor data 42 correlated tosensed conditions (Block 204). Location data 44 corresponding to thelocation of each detection unit 12 is then actively determined (Block206). The sensor data 42 and the location data 44 are then communicatedto the control centre 14 (Block 208). Next, the data 42, 44 is analyzedand a threat level correlated to the sensor data 42 is determined (Block210). A graphical display may then be generated which is correlated toboth the sensor data 42 and the location data 44.

Thus, while what is shown and described herein constitute preferredembodiments of the subject invention, it should be understood thatvarious changes can be made without departing from the subjectinvention, the scope of which is defined in the appended claims.

1. A detection system comprising: a) at least one detection unit,wherein the detection unit comprises: i) at least one sensor configuredto generate sensor data correlated to sensed conditions; ii) locator foractively determining location data corresponding to the location of thedetection unit; and iii) a communicator configured to communicate thesensor data and the location data, b) a control centre, wherein thecontrol centre comprises: i) a receiver for receiving the sensor dataand the location data; ii) a control processor configured to determine athreat level correlated to the sensor data, and c) a data storage unitoperatively coupled to the control centre and configured to storethreshold data, wherein the threshold data is correlated to previouslystored sensor data and correlated location data.
 2. The detection systemof claim 1, further comprising a communications network configured toprovide a communications link between the communicator and the receiver.3. The detection system of claim 1, wherein the detection unit furthercomprises a timer for generating timing data correlated to the time atwhich the sensor data is generated.
 4. The detection system of claim 1,wherein the threshold data comprises at least one data pointcorresponding to a predetermined threshold level.
 5. The detectionsystem of claim 1, further comprising a monitor operatively coupled tothe control processor, wherein the monitor is configured to generate agraphical display correlated to the sensor data and correspondinglocation data.
 6. The detection system of claim 5, wherein the graphicaldisplay comprises a map.
 7. A detection unit comprising: a) at least onesensor configured to generate sensor data correlated to sensedconditions; b) a locator configured to actively determine location datacorresponding to the location of the detection unit; c) a communicatoroperatively coupled to the sensor and to the locator, and configured tocommunicate the sensor data and location data; and d) a data storageunit operatively coupled to the sensor and configured to store thresholddata, wherein the threshold data is correlated to previously storedsensor data and correlated location data.
 8. The detection unit of claim7, further comprising a timer for generating timing data correlated tothe time at which the sensor data is generated.
 9. The detection unit ofclaim 7, wherein the threshold data comprises at least one data pointcorresponding to a predetermined threshold level.
 10. The detection unitas claimed in claim 7, wherein the location determining means comprisesa global positioning system.
 11. The detection unit as claimed in claim7, wherein the at least one sensor is configured to sense at least onefrom the following set of types of agents: chemical, biological,radiological and nuclear.
 12. A method of detecting threateningconditions, comprising the steps of: a) providing a control centre; b)providing at least one mobile detection unit, wherein the detection unitcomprises at least one sensor configured to generate sensor datacorrelated to sensed conditions; c) actively determining location datacorresponding to the location of the detection unit; d) communicatingthe sensor data and the location data to the control centre; e)providing threshold data correlated to previously stored sensor data andcorrelated location data; and f) determining a threat level correlatedto the sensor data, wherein said threat level determination comprisescomparing the sensor data generated in step b) to the threshold datacorresponding to the location data determined in step c).
 13. The methodas claimed in claim 12, further comprising the step of generating agraphical display correlated to both the sensor data and the locationdata.